This paper extends our previous work on formalizing event orderings using partial order set and its application in space analysis in distributed simulation. We focus on the time and space trade-off in exploiting event parallelism. Event parallelism is divided into inherent (problem) parallelism, event ordering parallelism and effective event parallelism. Firstly, we analyze the performance cost of varying event ordering parallelism on memory requirement in open and closed systems. Secondly, we study the effects of interconnection topology of a physical system on exploitable event ordering parallelism. Measurements were obtained from a time-space analyzer that we have developed.